Added response validation exception type

sdk/entra/Microsoft.Azure.WebJobs.Extensions.AuthenticationEvents/src/AuthenticationEventResponseHandler.cs

@@ -57,7 +57,7 @@ public Task SetValueAsync(object result, CancellationToken cancellationToken)
             {
                 if (result == null)
                 {
-                    throw new ArgumentNullException("AuthenticationEventResponseHandler", AuthenticationEventResource.Ex_Invalid_Return);
+                    throw new ResponseValidationException(AuthenticationEventResource.Ex_Invalid_Return);
                 }
 
                 if (result is AuthenticationEventResponse action)

sdk/entra/Microsoft.Azure.WebJobs.Extensions.AuthenticationEvents/src/Common/Exceptions/ResponseValidationException.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+
+namespace Microsoft.Azure.WebJobs.Extensions.AuthenticationEvents
+{
+    /// <summary>
+    /// Exception class for response validations
+    /// </summary>
+    public class ResponseValidationException : Exception
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ResponseValidationException"/> class.
+        /// </summary>
+        /// <param name="message"></param>
+        public ResponseValidationException(string message)
+            : base(message) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ResponseValidationException"/> class.
+        /// </summary>
+        /// <param name="message"></param>
+        /// <param name="innerException"></param>
+        public ResponseValidationException(string message, Exception innerException)
+            : base(message, innerException) { }
+    }
+}

sdk/entra/Microsoft.Azure.WebJobs.Extensions.AuthenticationEvents/tests/Payloads/TokenIssuanceStart/NullResponse.json

@@ -1,3 +1,3 @@
 {
-  "errors": [ "Return type is invalid, please return either an AuthEventResponse, HttpResponse, HttpResponseMessage or string in your function return. (Parameter 'AuthenticationEventResponseHandler')" ]
+  "errors": [ "Return type is invalid, please return either an AuthEventResponse, HttpResponse, HttpResponseMessage or string in your function return." ]
 }